A. Technical Field
The present invention relates to: a water-swellable crosslinked polymer, which is excellent in absorption capacity under an increased pressure; a production process for this polymer; and a measurement method for a pore volume of a swollen crosslinked polymer.
B. Background Art
In recent years, high water-absorbent resins with a high degree of water absorbency have been developed and are in practical use as disposable diapers, sanitary napkins, and so on by combining the high water-absorbent resins with fibrous base matters such as cotton, pulp, paper, and sponge.
However, these high water-absorbent resins have problems in that even if they display high absorption capacity by themselves, they do not necessarily display high absorption capacity when actually used as disposable diapers and so on. That is to say, when actually used, the resins are put under an increased pressure in a state combined with fibrous matters, so factors other than absorption by the resins alone give affections.
A method for enhancing the absorption capacity under an increased pressure is disclosed in Japanese Patent Application Publication (Kokai) No. 61-16903 and so on. In actual circumstances, however, this method is still not sufficient.